Pedestrians in new surroundings are often unable to efficiently navigate between desired locations. Indeed, in some cases such a pedestrian cannot even identify their current location with any accuracy. Pedestrian navigation while outdoors is fairly easy to address using radio networks. For example, global navigation satellite systems (GNSS) give worldwide coverage with an accuracy level of approximately 10 meters. Cellular networks provide a rough position in the order of hundreds meters. Similarly, WiFi networks can be mapped and used for localization with an accuracy of around 30 meters.
While GNSS may be suitable for short periods, mobile devices have limited power resources, and continuous use of GNSS for localization will quickly drain the device batteries. In addition, GNSS are not available indoors. The use of WiFi requires extensive mapping, which is possible some cases, but is not possible in certain critical applications such as guiding rescue personnel. Further, in surveillance applications, whether indoors or outdoors, continuous logging of the position is needed. In short, navigation protocols that use outside aids such as GNSS and WiFi are undesirable in many applications.
Pedestrian navigation that does not rely upon outside aids is referred to as pedestrian dead-reckoning (PDR). In this technique, a step detector may be used to count the number of steps taken by the user. Given an approximate step length, the traveled distance is calculated as proportional to the number of steps. However, to resolve a traveled trajectory, the heading (direction of movement) is also needed. Although most portable electronic devices can determine their own orientation, the relative orientation of the device with respect to the body of the pedestrian depends on the user. In general, the direction of user movement (heading) is not the same as the direction indicated by device orientation. Regardless, the device may swinging unpredictably as the user walks, further reducing the efficacy of using device orientation to determine user heading if the swinging motion is not compensated.
While the present disclosure is directed to a system that can eliminate certain shortcomings noted in this Background section, it should be appreciated that such a benefit is neither a limitation on the scope of the disclosed principles nor of the attached claims, except to the extent expressly noted in the claims. Additionally, the discussion of technology in this Background section is reflective of the inventors' own observations, considerations, and thoughts, and is in no way intended to accurately catalog or comprehensively summarize any item of prior art.
As such, the inventors expressly disclaim this section as admitted or assumed prior art with respect to the discussed details. Moreover, the identification herein of a desirable course of action reflects the inventors' own observations and ideas, and should not be assumed to indicate an art-recognized desirability.